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Kim JH, Lim ST, Shim GH, Lee GW, Kim S, Kim N, Wongwises S, Ahn HS. Virtual Loudspeaker Effect of Graphene-Based Hybrid Material To Improve Low-Frequency Acoustic Performance. ACS APPLIED MATERIALS & INTERFACES 2019; 11:35941-35948. [PMID: 31507173 DOI: 10.1021/acsami.9b07965] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Closed-box loudspeaker systems (CBLSSs) are compact and simple air-suspension loudspeaker systems, and their low-frequency responses are determined by two fundamental parameters: resonance frequency and total damping. Recently, electronic devices have come to require more compact designs, so the volumes of loudspeaker should be reduced. However, a small loudspeaker cannot retain sufficient acoustic space, resulting in poor low-frequency acoustic performance. Herein, we investigated acoustic characterization of the CBLSS with different filling materials such as thermally expanded graphene oxide (TEGO), activated carbon, graphene platelets, and melamine foam (MF). Upon the powder-based test, the resonance frequency of the loudspeaker decreased and resulted in a volume increasing effect inside of the loudspeaker. The TEGO shows almost double volume increase rate, compared to other particle-based filling materials. Employing hybrid filling material that consists of TEGO in an MF cage (TEGO@MF), the volume increase rate of the novel loudspeaker was over 24% at 300 cc. Because of the high adsorptive characteristics and thermal properties of TEGO, the acoustic performance in the low-frequency domain was clearly enhanced, despite the reduced mass loading. Furthermore, these properties were observed to be highly effective for enhancing the low-frequency acoustic performance of the larger loudspeaker, achieving a volume increase rate of 49.5% in a 700 cc enclosure.
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Affiliation(s)
- Ji Hoon Kim
- Department of Mechanical Engineering , Incheon National University , Academy-ro, Yeonsu-gu, Incheon 22012 , Republic of Korea
| | - Sun Taek Lim
- Department of Mechanical Engineering , Incheon National University , Academy-ro, Yeonsu-gu, Incheon 22012 , Republic of Korea
| | - Gyu Hyeon Shim
- Department of Mechanical Engineering , Incheon National University , Academy-ro, Yeonsu-gu, Incheon 22012 , Republic of Korea
| | - Gil Won Lee
- Department of Mechanical Engineering , Incheon National University , Academy-ro, Yeonsu-gu, Incheon 22012 , Republic of Korea
| | - Sungjoo Kim
- SAMSUNG Electronics Company Limited , Samsung-ro, Yeongtong-gu, Suwon-si 16677 , Gyenggi-do , Republic of Korea
| | - Namkeun Kim
- Department of Mechanical Engineering , Incheon National University , Academy-ro, Yeonsu-gu, Incheon 22012 , Republic of Korea
| | - Somchai Wongwises
- Department of Mechanical Engineering , King Mongkut's University of Technology Thonburi , Bangkok 10140 , Thailand
| | - Ho Seon Ahn
- Division of Thermal and Fluids Science, Institute for Computational Science; Faculty of Electrical and Electronics Engineering , Ton Duc Thang University , Ho Chi Minh City 700000 , Vietnam
- Department of Mechanical Engineering , Incheon National University , Academy-ro, Yeonsu-gu, Incheon 22012 , Republic of Korea
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Weltsch O, Offner A, Liberzon D, Ramon GZ. Adsorption-Mediated Mass Streaming in a Standing Acoustic Wave. PHYSICAL REVIEW LETTERS 2017; 118:244301. [PMID: 28665661 DOI: 10.1103/physrevlett.118.244301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Indexed: 06/07/2023]
Abstract
Oscillating flows can generate nonzero, time-averaged fluxes despite the velocity averaging zero over an oscillation cycle. Here, we report such a flux, a nonlinear resultant of the interaction between oscillating velocity and concentration fields. Specifically, we study a gas mixture sustaining a standing acoustic wave, where an adsorbent coats the solid boundary in contact with the gas mixture. It is found that the sound wave produces a significant, time-averaged preferential flux of a "reactive" component that undergoes a reversible sorption process. This effect is measured experimentally for an air-water vapor mixture. An approximate model is shown to be in good agreement with the experimental observations, and further reveals the interplay between the sound-wave characteristics and the properties of the gas-solid sorbate-sorbent pair. The preferential flux generated by this mechanism may have potential in separation processes.
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Affiliation(s)
- Oren Weltsch
- Nancy and Stephen Grand Technion Energy Program and Department of Civil and Environmental Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Avshalom Offner
- Nancy and Stephen Grand Technion Energy Program and Department of Civil and Environmental Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Dan Liberzon
- Nancy and Stephen Grand Technion Energy Program and Department of Civil and Environmental Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Guy Z Ramon
- Nancy and Stephen Grand Technion Energy Program and Department of Civil and Environmental Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
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Nori M, Venegas R, Raspet R. Acoustic frequency response method for the measurement of fast adsorption – Diffusion processes. Theoretical treatment. Chem Eng Sci 2017. [DOI: 10.1016/j.ces.2017.01.062] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Venegas R, Umnova O. Influence of sorption on sound propagation in granular activated carbon. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2016; 140:755. [PMID: 27586708 DOI: 10.1121/1.4959006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Granular activated carbon (GAC) has numerous applications due to its ability to adsorb and desorb gas molecules. Recently, it has been shown to exhibit unusually high low frequency sound absorption. This behavior is determined by both the multi-scale nature of the material, i.e., the existence of three scales of heterogeneities, and physical processes specific to micro- and nanometer-size pores, i.e., rarefaction and sorption effects. To account for these processes a model for sound propagation in GAC is developed in this work. A methodology for characterizing GAC which includes optical granulometry, flow resistivity measurements, and the derivation of the inner-particle model parameters from acoustical and non-acoustical measurements is also presented. The model agrees with measurements of normal incidence surface impedance and sound absorption coefficient on three different GAC samples.
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Affiliation(s)
- Rodolfo Venegas
- Carbon Air Ltd., The Innovation Forum, 51 Frederick Road, Salford M6 6FP, England
| | - Olga Umnova
- Acoustics Research Centre, University of Salford, Salford M5 4WT, England
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